1. Field of the Invention
This invention relates to structures of keyboard musical instruments such as electronic grand pianos.
This application claims priority on Japanese Patent Application No. 2003-57133.
2. Description of the Related Art
Conventionally, various electronic pianos such as electronic grand pianos have been developed to simulate real key touch (e.g., real key-touch feeling or sensation) actualized on acoustic grand pianos by using actions simulating actions of acoustic grand pianos, examples of which are disclosed in Japanese Patent Application Publication No. Hei 9-179545 (which claims priority on Japanese Patent Application No. Hei 7-280744, and which corresponds to U.S. Pat. No. 6,054,641), and the paper entitled “DGP-2XG Electronic Grand Piano Manual” published by Yamaha Corporation in the year 2001.
In the aforementioned electronic grand piano, adjusting of actions is an important factor to define the sound quality, wherein actions are arranged to provide the user (or player) with real key-touch feelings so that actual sounds are produced electronically. Specifically, a typical example of the electronic grand piano comprises various sensors for detecting operations of keys and hammers, so that musical tone signals are synthesized and produced based on detection results of the sensors. Synthesizing musical tone signals naturally require electronic circuits and components such as a control circuit for a sound source circuit (or a tone generator), an amplifier, and a speaker (or speakers). In the conventional electronic grand piano, the aforementioned electronic circuits and components are independently built in the main body (i.e., the casing or housing of the musical instrument) and are connected together via mutual wiring therebetween.
Prior to the completion in assembling electronic circuits and components, the main body of the electronic grand piano should be approximately completed in assembly (or in production). For this reason, it may be possible for an inspector to check operations of a power transformer, a sound source circuit, and other individual parts with ease during the production thereof; however, it may be difficult to check the overall operation of the assembly of electronic circuits and components. In order to install a relatively heavy component (e.g., a power transformer) in the lower side of the grand piano, it is necessary for the worker to assemble them by (manually) supporting them at prescribed positions. This deteriorates workability in the production of the electronic grand piano. That is, there occur various risks for a single worker in assembling mechanical and electronic parts together; thus, multiple workers should be necessary in order to assemble them together with safety.